From what I've read so far, clutch engagement can be trial and error, and driver experience dependent.
Jr champ, with a freshly rebuilt wka stock purple plate animal.
Track is approximately 1/20 of a mile narrow oval. 7 second lap times are normal-ish. 10 year old driver on his 4th year of competing.
In the previous 2 seasons, rookie crew chief dad, didn't realize the motor was deteriorating to the extreme. When engine re-builder believes even when it was healthy, it likely was not built with the purple plate in mind.
Last season. Varied between running 12/72 and 11/72 gear ratio. Hilliard clutch with either 2 black/2 white springs, or 4 black. The 11/73 was preferred, but the lack of roller bearing in the 11 could cause pre-mature lock up in long races or races with many stops. In that time I never hear the motor hit the rev limit.
This year with the new rebuild, the motor is noticeably stronger. We ran 12/72 (2 black/2 white) for the first race, as I had done a million things to the kart over the winter, and just wanted a reliable known starting point. To my surprise, my son won the feature, but 2nd place finisher was tight on his bumper. The track is not easy to pass on due to the small size. 2nd place finisher is known to be quick, but a very clean racer and did not push to pass, though I think he was quicker.
In practice the kart actually bounced off the rev limiter at the end of the straight, two rev cuts. In the heat and feature race, I couldn't hear the rev cut, but my son believes he heard it.
In my brief history of karting, I know the goal is to get close to rev cut at the end of the straight, but do you actually want to hit it?
Gear and clutch engagement are variables that I can control, I assume it's wise to only mess with one variable per race to see if there is a gain.
My plan is to try all black springs next race, however part of me thinks that will just make it hit the rev limiter sooner. Do you all think that is a wise first step?
After I see what the black springs do, then my thought is to adjust the gearing. If it hits the rev cut sooner, then I drop the axle gear down to 70. If it doesn't hit rev cut, then raise the axle gear, or lower the clutch gear to 11. If possible I want to avoid the 11.
It's probably time to invest in a mychron 4 as well, otherwise I'm just guessing, as a stopwatch isn't consistent enough with such a small track, and knowing what the revs are doing consitently would be better than using my untrained ear.
One other concern that might affect things, and I don't have the experience to know. Chain tension. Likely was a touch tighter than I normally run. It was a new chain and figure it might work in a bit and loosen some, however it didn't seem like it. As a result, spinning the axle didn't seem as free. I feel like that resistance has to factor in.
Jr champ, with a freshly rebuilt wka stock purple plate animal.
Track is approximately 1/20 of a mile narrow oval. 7 second lap times are normal-ish. 10 year old driver on his 4th year of competing.
In the previous 2 seasons, rookie crew chief dad, didn't realize the motor was deteriorating to the extreme. When engine re-builder believes even when it was healthy, it likely was not built with the purple plate in mind.
Last season. Varied between running 12/72 and 11/72 gear ratio. Hilliard clutch with either 2 black/2 white springs, or 4 black. The 11/73 was preferred, but the lack of roller bearing in the 11 could cause pre-mature lock up in long races or races with many stops. In that time I never hear the motor hit the rev limit.
This year with the new rebuild, the motor is noticeably stronger. We ran 12/72 (2 black/2 white) for the first race, as I had done a million things to the kart over the winter, and just wanted a reliable known starting point. To my surprise, my son won the feature, but 2nd place finisher was tight on his bumper. The track is not easy to pass on due to the small size. 2nd place finisher is known to be quick, but a very clean racer and did not push to pass, though I think he was quicker.
In practice the kart actually bounced off the rev limiter at the end of the straight, two rev cuts. In the heat and feature race, I couldn't hear the rev cut, but my son believes he heard it.
In my brief history of karting, I know the goal is to get close to rev cut at the end of the straight, but do you actually want to hit it?
Gear and clutch engagement are variables that I can control, I assume it's wise to only mess with one variable per race to see if there is a gain.
My plan is to try all black springs next race, however part of me thinks that will just make it hit the rev limiter sooner. Do you all think that is a wise first step?
After I see what the black springs do, then my thought is to adjust the gearing. If it hits the rev cut sooner, then I drop the axle gear down to 70. If it doesn't hit rev cut, then raise the axle gear, or lower the clutch gear to 11. If possible I want to avoid the 11.
It's probably time to invest in a mychron 4 as well, otherwise I'm just guessing, as a stopwatch isn't consistent enough with such a small track, and knowing what the revs are doing consitently would be better than using my untrained ear.
One other concern that might affect things, and I don't have the experience to know. Chain tension. Likely was a touch tighter than I normally run. It was a new chain and figure it might work in a bit and loosen some, however it didn't seem like it. As a result, spinning the axle didn't seem as free. I feel like that resistance has to factor in.